1. Field of the Invention
The present invention relates to a thermal analysis apparatus for measuring thermal characteristics of a sample while controlling the temperature of the sample.
2. Description of the Related Art
There have been known various types of thermal analysis apparatuses, such as a TG (Thermogravimetory) apparatus, a DTA (Differential Thermal Analysis) apparatus, and a DSC (Differential Scanning Calorimetory) apparatus. The TG apparatus measures a weight change of a sample with respect to a temperature change or a time lapse. The DTA apparatus simultaneously heats a reference substance being stable in a thermal characteristics and a sample of interest, and then measures a temperature difference exhibited between the reference substance and the sample at the time when the sample reacts to a heat. Thus, the DTA apparatus can detect, based on the temperature difference occurred, a thermal change having been occurred in the sample. The DSC apparatus measures the amount of heat when endothermic reaction or exothermic reaction occurs in the sample while it is heated, cooled, or held at a constant temperature. In addition, there have been known apparatuses that analyze a gas generated from a substance while it is heated. Known as such apparatuses are a TG-MAS apparatus (meaning a thermo gravimetry and mass spectrometry apparatus), a TPD apparatus (meaning a temperature programmed desorption apparatus), and the like.
In the above apparatuses, a heating unit is used for heating a sample. For example, Japanese Patent Laid-Open Publication No. 4-361145 discloses, at pages 2 to 3 and in FIG. 1 thereof, a heating unit using a heater obtained by winding a heater wire around a cylindrical bobbin. In the thermal analysis apparatus using such a type of heating unit, a sample of interest has to be inserted into and removed from the inner heating region of the heating unit. For example, Japanese Patent Laid-Open Publication No. 2005-331432 discloses, at page 7 and in FIG. 2 thereof, a technique for facilitating the aforesaid inserting and removing operation for the sample. In the technique, a heating unit such as an electric furnace is moved so as to release the sample outside the heated region.
In recent years, conditions required for the thermal analysis apparatus has been diversified. More specifically, measurements under a specific environment have been required to be performed. Such a measurement may be, for example, a simultaneous measurement of the TG gas analysis and the DTA gas analysis or a measurement under a predetermined humidity atmosphere. In order to meet the diversification, many types of the heating units have been available, and a large number of accessories have been added to the heating unit. For example, tubes for carrying gas may be additionally provided to a heating unit for a gas analysis. Further, a humidity generator may be additionally provided to a heating unit for a humidity analysis. In such cases, the weight of the entire heating unit becomes large thereby to apply a large load on a mechanism for moving the heating unit. Thus, it becomes necessary to prepare a large-scaled moving mechanism capable of enduring a large load. Further, it is necessary to prepare and secure a space allowing tubes to move when the heating unit is moved. Since a conventional thermal analysis apparatus requires a large-scale moving mechanism and a space for allowing tubes or the like to move freely as mentioned above, there is a problem that the apparatus inevitably has a large-sized and a strongly-built construction.